Optical communication involves imprinting or encoding information on light, thereby adapting the light to carry or convey the information as the light propagates or travels between two sites. The two sites may be across the globe or across a country, a state, a town, or a room, for example.
Imprinting or encoding information on light typically involves varying, modulating, or changing some attribute or aspect of the light over time to create a pattern representing the information. A sender or transmitter of the information imposes the pattern on the light, and a receiver of the information identifies the pattern and thereby recovers the information.
For example, sailors on two distant ships may communicate with one another with powerful flashlights. One sailor pulses light on and off in a sequential pattern that represents letters of the alphabet, forming words and sentences, for example in Morse code. The other, distant sailor watches the light and notes the on-off pattern. Knowing the on-off sequences of each letter, that distant observer sailor determines the letters, words, and sentences via reversing the code. While modern fiber optic communication systems are more sophisticated than sailors sending messages to one another with flashlights, the basic concept is generally analogous.
A fiber optic communication system may comprise terminals or users linked together via optical paths, for example in a fiber optic network. Each terminal may comprise a transmitter and a receiver that may be components of a transceiver. Each terminal's transmitter typically outputs light imprinted or encoded with information destined for receipt at another, remote terminal. Meanwhile, each terminal's receiver typically receives light that has been imprinted or encoded with information at another, remote terminal. Accordingly, devices on an optical network can communication with one another via sending and receiving optical signals.
In most conventional optical communication systems, a laser emits the light onto which the information is encoded or imprinted. The encoded light exits the laser and propagates to the information recipient over transmission media that is outside and distinct from the laser. In many circumstances, the encoded light interacts with the transmission media in a manner that obscures the encoding or that otherwise complicates reception by the intended recipient. To mention a few examples, complicating phenomena can include chromatic dispersion, four-wave mixing, polarization mode dispersion, Brillouin scattering chirp, and non-linear interaction between the laser light and the transmission media. Other complications arise as a result of the lasing medium having a composition and optical properties that are significantly different from the transmission media. For example, conventional optical communication system often include an isolator (or a circulator) situated between the laser and the optical transmission media. The isolator prevents light propagating on the optical transmission media towards the laser from entering the laser. Isolators are often discrete devices with size and cost that are incompatible with many potential applications that could otherwise benefit from optical communication technology.
In view of the aforementioned representative deficiencies in the art (or some other related shortcoming), need exists for an improved optical communication system that is compact, that reduces the number or complexity of elements, and/or that integrates an optical transmission medium with a lasing or a gain medium. A technology addressing one or more such needs would benefit optical communications, for example via providing lower cost, better access to higher bandwidth, new applications, reduced size, lower power consumption, higher levels of integration, better manufacturability, etc.